Add plugin functionality for link-time optimization (LTO).

include/:
	* plugin-api.h: New file.

gold/:
	* configure.ac (plugins): Add --enable-plugins option.
	* configure: Regenerate.
	* config.in: Regenerate.
	* Makefile.am (LIBDL): New variable.
	(CCFILES): Add plugin.cc.
	(HFILES): Add plugin.h.
	(ldadd_var): Add LIBDL.
	* Makefile.in: Regenerate.

	* archive.cc: Include "plugin.h".
	(Archive::setup): Don't preread archive symbols when using a plugin.
	(Archive::get_file_and_offset): Add memsize parameter.  Change callers.
	(Archive::get_elf_object_for_member): Call plugin hooks for claiming
	files.
	(Archive::include_member): Add symbols from plugin objects.
	* archive.h (Archive::get_file_and_offset): Add memsize parameter.
	* descriptors.cc (Descriptors::open): Check for file descriptors
	abandoned by plugins.
	(Descriptors::claim_for_plugin): New function.
	* descriptors.h (Descriptors::claim_for_plugin): New function.
	(Open_descriptor::is_claimed): New field.
	(claim_descriptor_for_plugin): New function.
	* fileread.cc (File_read::claim_for_plugin): New function.
	* fileread.h (File_read::claim_for_plugin): New function.
	(File_read::descriptor): New function.
	* gold.cc: Include "plugin.h".
	(queue_initial_tasks): Add task to call plugin hooks for generating
	new object files.
	* main.cc: Include "plugin.h".
	(main): Load plugin libraries.
	* object.h (Pluginobj): Declare.
	(Object::pluginobj): New function.
	(Object::do_pluginobj): New function.
	(Object::set_target): New function.
	* options.cc: Include "plugin.h".
	(General_options::parse_plugin): New function.
	(General_options::General_options): Initialize plugins_ field.
	(General_options::add_plugin): New function.
	* options.h (Plugin_manager): Declare.
	(General_options): Add --plugin option.
	(General_options::has_plugins): New function.
	(General_options::plugins): New function.
	(General_options::add_plugin): New function.
	(General_options::plugins_): New field.
	* plugin.cc: New file.
	* plugin.h: New file.
	* readsyms.cc: Include "plugin.h".
	(Read_symbols::do_read_symbols): Check for archive before checking
	for ELF file.  Call plugin hooks to claim files.
	* resolve.cc (Symbol_table::resolve): Record when symbol is referenced
	from a real object file; force override when processing replacement
	files.
	* symtab.cc (Symbol::init_fields): Initialize in_real_elf_ field.
	(Symbol::init_base_object): Likewise.
	(Symbol::init_base_output_data): Likewise.
	(Symbol::init_base_output_segment): Likewise.
	(Symbol::init_base_constant): Likewise.
	(Symbol::init_base_undefined): Likewise.
	(Symbol::output_section): Assert that object is not a plugin.
	(Symbol_table::add_from_pluginobj): New function.
	(Symbol_table::sized_finalize_symbol): Treat symbols from plugins as
	undefined.
	(Symbol_table::sized_write_globals): Likewise.
	(Symbol_table::add_from_pluginobj): Instantiate template.
	* symtab.h (Sized_pluginobj): Declare.
	(Symbol::in_real_elf): New function.
	(Symbol::set_in_real_elf): New function.
	(Symbol::in_real_elf_): New field.
	(Symbol_table::add_from_pluginobj): New function.

	* testsuite/Makefile.am (AM_CFLAGS): New variable.
	(LIBDL): New variable.
	(LDADD): Add LIBDL.
	(check_PROGRAMS): Add plugin_test_1 and plugin_test_2.
	(check_SCRIPTS): Add plugin_test_1.sh and plugin_test_2.sh.
	(check_DATA): Add plugin_test_1.err and plugin_test_2.err.
	(MOSTLYCLEANFILES): Likewise.
	* testsuite/Makefile.in: Regenerate.
	* testsuite/plugin_test.c: New file.
	* testsuite/plugin_test_1.sh: New file.
	* testsuite/plugin_test_2.sh: New file.

1 files changed, 48 insertions, 28 deletions

diff --git a/gold/readsyms.cc b/gold/readsyms.cc
index 05c80f8ff7..ac646d95d1 100644
--- a/gold/readsyms.cc
+++ b/gold/readsyms.cc
@@ -32,6 +32,7 @@
 #include "archive.h"
 #include "script.h"
 #include "readsyms.h"
+#include "plugin.h"
 
 namespace gold
 {
@@ -159,6 +160,53 @@ Read_symbols::do_read_symbols(Workqueue* workqueue)
   const unsigned char* ehdr = input_file->file().get_view(0, 0, read_size,
 							  true, false);
 
+  if (read_size >= Archive::sarmag)
+    {
+      bool is_thin_archive
+          = memcmp(ehdr, Archive::armagt, Archive::sarmag) == 0;
+      if (is_thin_archive 
+          || memcmp(ehdr, Archive::armag, Archive::sarmag) == 0)
+	{
+	  // This is an archive.
+	  Archive* arch = new Archive(this->input_argument_->file().name(),
+				      input_file, is_thin_archive,
+				      this->dirpath_, this);
+	  arch->setup(this->input_objects_);
+	  
+	  // Unlock the archive so it can be used in the next task.
+	  arch->unlock(this);
+
+	  workqueue->queue_next(new Add_archive_symbols(this->symtab_,
+							this->layout_,
+							this->input_objects_,
+							this->mapfile_,
+							arch,
+							this->input_group_,
+							this->this_blocker_,
+							this->next_blocker_));
+	  return true;
+	}
+    }
+
+  if (parameters->options().has_plugins())
+    {
+      Pluginobj* obj = parameters->options().plugins()->claim_file(input_file,
+                                                                   0, filesize);
+      if (obj != NULL)
+        {
+          // The input file was claimed by a plugin, and its symbols
+          // have been provided by the plugin.
+	  input_file->file().claim_for_plugin();
+	  input_file->file().unlock(this);
+          workqueue->queue_next(new Add_plugin_symbols(this->symtab_,
+                                                       this->layout_,
+                                                       obj,
+                                                       this->this_blocker_,
+                                                       this->next_blocker_));
+          return true;
+        }
+    }
+
   if (read_size >= 4)
     {
       static unsigned char elfmagic[4] =
@@ -201,34 +249,6 @@ Read_symbols::do_read_symbols(Workqueue* workqueue)
 	}
     }
 
-  if (read_size >= Archive::sarmag)
-    {
-      bool is_thin_archive
-          = memcmp(ehdr, Archive::armagt, Archive::sarmag) == 0;
-      if (is_thin_archive 
-          || memcmp(ehdr, Archive::armag, Archive::sarmag) == 0)
-	{
-	  // This is an archive.
-	  Archive* arch = new Archive(this->input_argument_->file().name(),
-				      input_file, is_thin_archive,
-				      this->dirpath_, this);
-	  arch->setup(this->input_objects_);
-	  
-	  // Unlock the archive so it can be used in the next task.
-	  arch->unlock(this);
-
-	  workqueue->queue_next(new Add_archive_symbols(this->symtab_,
-							this->layout_,
-							this->input_objects_,
-							this->mapfile_,
-							arch,
-							this->input_group_,
-							this->this_blocker_,
-							this->next_blocker_));
-	  return true;
-	}
-    }
-
   // Queue up a task to try to parse this file as a script.  We use a
   // separate task so that the script will be read in order with other
   // objects named on the command line.  Also so that we don't try to